The art of cupping requires heavy die sets and a large press. Die sets of the triple action type include the usual components, such as blanking and draw punches and die blocks and stripper plates, and all those details disposed on a die shoe and a blanking punch holder plate in a double-acting press above and below a movable sheet of metal stock.
Several problems have been encountered with multiple cupping tooling presently in use. The tooling of each die set therein must be aligned precisely to meet close tolerances required, and consequently the punches and die blocks of each die set must be rigidly retained within their respective holder plate and die shoe by bolting the die blocks directly to their corresponding backup members. As a result, wrench clearances used to install bolts and nuts in the assembly of die sets, in general, present difficult access situations for tooling changes, which multiple die cupping only compounds because of the necessity of close nesting of multiple die sets to conserve sheet stock material.
Another problem that results with multiple cupping tooling is that the die blocks, including the die shoes, are very heavy and each must be completely dismantled and separately removed from the press every time there is need for repair or replacement. This creates considerable down time, on the order of one and a half to two hours, because extra care must be taken in fastening the parts together in precise alignment. As a result, valuable production time is wasted.